Step 1: Trim the root ends of the leeks, and cut the tops off just above where the dark green starts. Cut a slit lengthwise down the leek, going about halfway into it, and rinse thoroughly in cold water to remove any grit.

Step 2: Bring a pan of water to boil. Salt it. Tie the leeks in bundles so they don’t fall apart, and gently boil, covered, until tender, about 10 minutes, depending on their size.

Step 3: Drain and rinse under ice-cold water to preserve their colour. Drain thoroughly, pat dry with a towel, and refrigerate until about an hour before serving.

Step 4: For the vinaigrette, macerate the shallot in enough vinegar to cover for 10 minutes. Drain off the vinegar.

Step 5: Stir the mustard and oil into the shallots, and season well. Taste, adding more oil or vinegar to balance as needed.

Step 6: Arrange the leeks on a serving platter. Spoon over the vinaigrette. Shave over lemon zest and Parmesan cheese, then finish with a grinding of pepper.